Population III stars, the first light sources in the Universe, start
the epoch of reionization and the chemical enrichment of the
interstellar medium. Their properties and formation history thus
contribute shaping the environment in which galaxies form later. I
will discuss their formation at very high redshift highlighting the
spatial distributions of their remnants --- most probably intermediate
mass black holes --- and their link with AGN activity at redshift z~6.
Finally I will discuss the possibility of a long tail in the epoch of
Population III star formation, made possible by the existence of
pockets of pristine primordial gas in galaxy voids down to redshift z~1.